Protective effect of young green barley leaf (Hordeum vulgare L.) on restraint stress‑induced decrease in hippocampal brain‑derived neurotrophic factor in mice

Background: Many health experts support the hypothesis that stressful lifestyles are the leading cause of illness, like depression. Therefore, from the standpoint of preventive medicine, it is important to reduce stress. Young green barley leaves are a good natural source of vitamins and minerals, and their juice is widely consumed as a functional food for health reasons in Japan. This study investigated the protective effect of young green barley leaves for stress control. Materials and Methods: ICR outbred mice were exposed to 3‑h sessions of restraint stress. Young green barley leaves (400 and 1,000 mg/kg) were administered orally 1 h before the sessions for 5 days. To analyze voluntary behavior, wheel‑running activity was monitored during the dark period. Brain‑derived neurotrophic factor (BDNF) messenger RNA (mRNA) expression in the whole hippocampus was measured by real‑time quantitative polymerase chain reaction. Results: Restraint stress resulted in a significant decrease in voluntary wheel‑running behavior, but this decrease was ameliorated by the administration of young green barley leaves. The leaves also enhanced the decreased levels of BDNF mRNA induced by restraint stress; in particular, a significant protective effect was shown in the exon IV variant as compared to vehicle control mice. Conclusion: The findings suggest that young green barley leaves have potent anti‑stress properties, as evidenced by preventing decreases in the levels of voluntary wheel‑running activity and hippocampal BDNF mRNA in response to restraint stress. Our findings support the possibility that supplementation with young green barley leaves might be beneficial for preventing stress‑related psychiatric disorders like depression.